The other week I was walking through a neighbourhood in Turku, Finland and a bunch of cars just stood out to me, enough to grab a photo for Twitter. One of them was a late model Saab 9-3 convertible with “Aero TTiD” proudly affixed on its trunk lid. What a concept! The idea of a diesel convertible suddenly sent my mind spinning like the blades of a turbocharger. By itself, a convertible car is something frivolous. You take a structure of a car and leave a bit of it out, so it’s open like a bathtub for everything above it, from the sun to rain to leaves and smells to enter it. The convertible part of the name comes from the fact you can convert a car from said bathtub to something that will theoretically hold water and keep wind outside, and again back to a bathtub, either manually or with a powered folding roof. It’s great to have a convertible or a roadster because you can visit the same places as with a fixed roof car but getting exposed to the elements at the same time. There is no cocooning feeling, you experience everything around you with no filter. Except for glass, but who drives an open car with the windows up?

Remember diesel convertibles pic.twitter.com/B9nJh5a5dU

— Antti ”Antti Gauchonen” Kautonen (@julkinen) July 25, 2021

But by introducing a diesel engine to the mix, you turn the vision of an impractical, frivolous, open-spirited car upside down. You’re using an industrial engine running on heavy oil! The beating heart of your open car is from a van! The diesel smells both going in as a liquid and coming out of the car in exhaust form. If there’s no particulate filter, the exhaust is a black cloud when you use the enticing levels of turbodiesel power. If there is a particulate filter, it needs to burn itself clean at some point and you have another black cloud coming. Considering our taxation here, to have diesel make financial sense, you have to do a lot of driving for the cheap fuel to overcome the heftier road tax. But our weather isn’t really compatible with convertible driving with the top down except for short periods in “summer”, so you must keep the top up unless you’re the kind of guy to keep it down all the time no matter what the weather is. But then you must be insane, which makes you less likely to drive something frugal, to begin with.

So, naturally, I love the idea of a diesel convertible. Like I mentioned in my recent Volvo article, I do a lot of commuting these days, driving 100 miles per day whenever I need to visit the office, and if it’s just me in the car it doesn’t necessarily need to be a wagon, right? There are several drop-top diesels that would suit this purpose, from the Saab in the opening paragraph to the Volvo C70 D5, which combines an S40-derived platform with the D5 engine / M66 gearbox combination I now know and love. The 2.4 I5 turbodiesel might even sound good in a convertible! However, the Volvo is of “coupe convertible”, or CC configuration, which often does great work of turning regular cars into something with the dimensions of a Ferrari Mondial except with a taller window line and an even more unreliable roof system. This is especially the case with some French offerings, but the Saab has a normal cloth roof instead of a body colour panel job.

Diesel passenger cars have rapidly been falling out of fashion in recent years due to headline-grabbing emissions issues, which have nixed diesel’s chances of being the fuel of the future and fast-forwarded manufacturer electrification to take its place. At the same time, decidedly rental car-looking convertibles have also become rarer, if not yet completely obsolete. The combination of the two is rare these days, but you can for example get the BMW 4 Series as a humbler 420d convertible or properly mad-hat M440d xDrive with 335hp and 700Nm/516 lb-ft of torque. But still, I’d classify diesel convertibles as a definite “Early 2000s European thing”, something that is worth a Hooniverse article if nothing else.

[Photos: Volvo, Peugeot]